Process for production of lubricating oil



Jan. 22, 1935. u. B. BRAY ET AL 1,938,712

PROCESS FOR PRODUCTION OF LUBRICATING' OIL Filed Aug. 4, 1931 4Sheets-Sheet 1 O O 0880 Owgm 'IVQH'EIAIND .LIOHAVS' ALISODSIA v.INVENTORS Ulric BBrg/ Claude flaw/2%.

ATTQRNEY.

E ow on ow am cm 2 0 Jan. 22, 1935. u. B. BRAY ET AL Y PROCESS FORPRODUCTION OF LUBRiCATING OIL Filed Aug. 4, 1931 4 Sheets-Sheet 2' MAY 4w. w. W 8

md n w A aw 9 3 VB Y 5 .w v w Jan. 22, 1935.

U. B BRAY ET AL PROCESS FOR PRODUCTION OF LUBRICATING OIL Filed Aug. 4,1951 4 Sheets-Sheet 5 INVENTORS Ulric 51m 4 Claude E sm'fi Y?v i Jan;22,1935. u. B. BRAY, ET AL 1,938,712

PROCESS FOR PRODUCTION OF LUBRICATING OIL ,fif d g. 4, 1931 4 Sheets-Sheet 4 INVENTORS Patented Jan. 22, 1935 I v UNITED STATES PROCESS FORPRODUCTION OF LUBRICATING OIL Ulric B. Bray, Palos Verdes Estates, andClaude E. Swift, Huntington Park, Califl, assignors to' Union OilCompany of California, Los Angeles, Calif., a corporation of CaliforniaApplication August 4, 1931, Serial No. 555,017

11 Claims. (Cl. 196-37) This invention relates to a method andapasphaltic crudes, containing no wax, have the paratus for treatingpetroleum to produce lubrislope on this 'chart, independent of theviscosity cating oil. of the oils at any given temperature. Thus an oilOne of" the distinctive characteristics of a-luhaving a viscositycorresponding to 600 seconds bricating oil is its viscosity. For manypurposes Saybolt Universal 'at'100 F. will have thesa'me 5 lubricantsare preferred which exhibit a minislope as an oil havingaviscosity of1000 seconds mum variation in viscosity with variations in SayboltUniversal at 100 F. Acid treatment of 'temperaturai. e., have lowviscosity temperature these oils has a tendency to flatten the curves,susceptibility. iIt is generally known that the i. e., making them lesssteep. The amount of viscosity of lubricating oil produced fromWestflattening will depend upon the degree of treat- 10 em crude, suchas. California naphthene base ment. We have found, however, that allcommercrudes, that is, crude containing asphalt varies cial Westernlubricating oils have substantially more with change in temperature thando lubrithe same slope Curve B of Fig. 2 illustrates eating oilsproduced from paraflin base crudes. the curve for a treated oil of theasphalt base That is, if two such oils have the same viscosity at ypehaving aybolt Universal viscosities of 600 15 100 F., the Western oilwill have a much lower seconds at 100 F. and 55 seconds at 210 F.viscosity at 210 F-. than will the paraffin base oil. Likewise es du llub icati g oils p d This change in viscosity with temperature is fromparafiin base crude oils, containingsubsometimes called the temperaturesusceptibility Stantially 110 asphalt Will have PD a Y of an oil. It isone of the characteristics of the same slope on this chart independentof the Western lubricating oils that they are distillates, v i y f theil at y given mp r t r that is, are vaporized from crude oil and con-However, as the viscosity of the residuum varies densed. Lubricatingoils produced from paraffin from 2000-5000 seconds, Saybolt Universal atbase oils, containing substantially no asphalt, 00 F., the S ope W l Vay from 2 to 5%. The

are generally produced by first distilling light par i ular bri ht k" nu v A f 2 h s 25 oils overhead including the kerosene and, gas oilSaybolt Universal viscosities of 2350 seconds at and also takingoverhead light lubricating oils 100 F. and 145 seconds at 210 F. calledneutrals having a viscosity in the neigh- That p p r y os d y er n mp nn borhood of 100-200 seconds, Saybolt Universal of an oil which impartsto it a slope approaching at 100 F'., leaving an undistilled residuetermed Curve A of Fig. 1 may be Said to be a measure 0f 30 bright stock.The oils of various viscosity are the paraflin base characteristicsexhibited by the made by blending these neutrals and bright oil. V 7stock in any desired proportion to obtain the It has been observed byone of us that many desired viscosity, oils containing asphalt and waxare mixtures of This variation in viscosity with temperaturehydrocarbons analogous both to the hydrocar- 35 can be best illustratedby reference to Fig. 1. bons present in parafiin base oils and thosepres- This chart is well known and is described and ent in asphalt baseoils. It has further been obshown in the International Critical Tables,Vol. Served by one of us that during the heating of 2, page 147. It is aspecial type of temperature an oil containing asphalt, the asphaltapparently 40 co-ordinate chart in which the abscissa scale is inducescertain chemical and perhaps certain 40 the logarithm of absolutetemperature and the physical reactions at relatively low temperaturesordinate scale is an additive function .of the which tend to destroy theinherent low viscosity viscosity which has been developedexperimentemperature susceptibility of the lubricating oil tally. Theresulting ordinate scale is a warped fractions. This apparent catalyticphenomena logarithm scale of the kinematic viscosity upon seems toexplain the observed changes although 45 which, for convenience, thecorresponding scale we do not wish to be understood as being bound ofSaybolt Universal viscosity has been superby this theory. It has beenobserved that these imposed. temperatures at which the changes appearare be- It is found as an experimental fact, that the low the vaporizingtemperatures in batch distilviscosity of any petroleum oil for varyingtemlation (vacuum or steam) of the lubricating oil 50 pcra urcs willfall on a straight line when plotted fractions which have SayboltUniversal viscosion this chart. The steeper the slope of the line, tiesabove 400-500, seconds at 100 F. It is safe the greater is the variationof the viscosity with to say that no oil containing asphalt can betemperature. topped to the point where fractions above 400-500Lubricating oils produced by distillation from seconds, SayboltUniversal viscosity at F. are 55 vaporized without a degeneration ofthose characteristics of the paraflin hydrocarbons which impart to theoil a low temperature viscosity susceptibility. During the distillationof the heavy oils in the presence of asphalt some change in molecularstructure or configuration takes place which is attended by a change ofviscosity temperature characteristics. This behavior is thought to bedue to pyrolytic reactions which are catalyzed by the presence ofasphalt. The above discovery is made the subject matter. of application,Serial No. 466,189. The lubricating oil components in the crude oilwhich have high paraillnbase characteristics, 1. e., similar to the oilrepresented by Curve A of Fig. 1, are converted by the distillation intooils exhibiting low paraffin base characteristics, 1. e., similar to theoil represented by Curve 3 of Fig. 1.

In order to preserve the inherent characteristic of the lubricating oilcomponents of crude oil containing asphalt which are impairedv bydistillation methods as previously described, we have. in accordancewith the process of -.the above application, caused the separation ofthe oil and wax from the asphalt by a method wherein the lubricating oilconstituents present in the crude oil are separated from the asphaltpresent in such a manner that the oil retains those characteristicswhich it possessed in the original crude oil. As a means of attainingthis end it has been found advisable to cause the separation of theasphalt from the oil by means of solvents which are capable ofdissolving the oil and which do not dissolve the asphalt. Such solventsare light petroleum fractions, such as naphtha, casinghead gasoline andpetroleum fractions normally vaporous at ordinary temperature andpressure. Other solvents which may be used are alcohol, ether,,mixturesof alcohol and ether, acetone, etc. We prefer to use as our solvent apetroleum fraction obtained by the rectification of natural gasoline.For most purposes a fraction composed of 6.72% ethane, 72.2% propane,19.91% iso butane and 1.17% normal butane is satisfactory. However, byusing a fraction containing a higher percentage of ethane it is possibleto produce a lubricating oil having a low Conradson carbon value. Such asolvent has a tendency to leave certain heavy oil fractions in theprecipitated asphalt which have a tendency to form a high carbonresidue. Such a fraction suitable for the production of a lubricatingoil having a low Conradson carbon value would contain ethane varying inquantities from 40 to 50% by volume. It will be understood, however,that these merely illustrate the type of fractions which may be used andthat the composition may vary. This fraction will hereinafter bereferred to as propane for purposes of simplicity.

In carrying out the extraction of the oil with this light liquidfraction the solution is maintained at a pressure sufficient tomaintainthe propane liquid at ordinary temperatures. The fraction describedabove is liquid at ordinary temperatures at a pressure of about poundsper square inch. The extraction of the oil from the petroleum at suchpressures results in an asphalt substantially free of oil, compoundchiefly of bitumen and a solution of oil and wax in the liquid petroleumfraction. The oil dissolved in the liquid propane contains substantiallyall of the lubricating oil components which are present in the crude oiland in substantially the same form as they exist in the original crude'oil and also the major portion of the wax present in the crude oil.

Before further discussion of this invention it will be best to deflne a'new term which we have found useful in identifying the oils of ourinvention. Curve C of Fig. 1 represents a typical oil which has beenextracted with propane from oil containing asphalt and wax. This curvehas a slope intermediate between curve A and curve B, i. e., a trueparaflin base bright stock, having for example, Saybolt Universalviscosities of 2350 seconds at 100 F. and seconds at 210 F., and a trueWestern lubricating oil having for example, Saybolt Universalviscosities at 600 seconds at 100 F. and 55 seconds at 210 F. Since theslopes of A and B are characteristic of all oils of like nature theabsolute viscosity is immaterial to our present purpose after the linesare once defined. We draw two lines on the chart parallelto curves A andB, respectively, passing through the intersection of curve A with the100 F. line. These curves are defined as curves A and B. The distancebetween their intercepts on-the 210 temperature ordinate line is takenas 100. The ratio of the intercept between curves C and B and theintercept between A and B gives the paraffin base characteristics of theoil corresponding to curve C. It will be observed that the curve C shows51% paraffin base characteristics.

We have discovered that many lubricating oils obtained by extractionwith solvents, for instance, propane, from crude oil containing asphaltand wax are composed of oils which are high in paraffin basecharacteristics, 1. e., have slopes approaching Curve A of Fig. 1, andoils low in paraflin base characteristics, i. e., have slopesapproaching Curve B of Fig. 1 and that these oils may be separated intooils which exhibit a low temperature viscosity susceptibility resemblingoils produced from non-asphalt containing crude and oils which exhibit ahigh temperature viscosity susceptibility corresponding to oils producedby' distillation. For convenience we will call the oils which havehigh-parafiin base characteristics separated into these respective oilsby the use of solvent agents which will selectively dissolve out thenon-paraffinoid components. We have found that certain solvents have a.selective solvent action for the non-parafiinoicl oils. As solventagents which will effect this separation we have found liquid sulphurdioxide, mixtures of acetone and benzol, aniline or methyl formateuseful. Acetone alone in addition to being an asphalt precipitant alsohas in some measure the ability to split the oil in the above manner.The use of liquid sulphur dioxide has been found especially valuable asa solvent to separate 'the propane extract into oils which exhibit highparaffin base characteristics and into oils which exhibit low paraffinbase characteristics. By subjecting the possess a high temperatureviscosity susceptibility. The toppedoil is first dissolved in. liquidpropane in.order tojseparatethe oil from the asphalt, after which the,wax is remove d. The propane solution o f oil is then agitated withtreating. quantities. of sulphuricacid after which the sludge formed isallowed to settleout. The propaneis then sep arated from.tl1e' acidtreated oil, after which the oil is cooledand treated with liquidsulphur dioxide toresolve it into a portion exhibiting high parafiinbase characteristics and a portion exhib-.

iting low-paraffin base characteristics. 7

.. V Vhi1 e' the above method of.v treating the oil with acid appears tobe preferable from an engineering standpoint, we have found that byperforming this step. in the process subsequent to treatment WithJiquidsuIphur dioxide that more effective results are obtained. ,By acidtreating the .oil prior to extraction with liquid sulphur, di-i oxide alarge portion of the acid is consumed in removing from the oilunsaturated bodies which are easily removable with liquid sulphurdioxide. By treating theoil with acid subsequent to extractionw'ithliquid sulphur dioxidethe acid.

utilized in such treatment is free to act upon those undesirable bodiespresent in the oil which are not removable by liquid sulphur dioxide.Thus by acid treating subsequent to extraction with sulphur dioxide weare able to obtain a more ECO:-

nomical use of acid and a more effective removal of undesirable bodiespresent in the oil.

One of the desirable qualities of a lubricating oil is a low Conradsoncarbon value. According to the United States Government Department ofCommerce, Bureau of Mines Technical paper 323B, page 86, thisvaluethrows some light upon the relative carbon forming properties of an oil.Oils which possess a low value have less tendency to cause carbondeposition in in-' ternal combustion. motors during use than do oilswhich possess a high value. In general, lubricating oils produced by theordinary distillation processes from crudes containing asphalt exhibit alow Conradson carbon value whereas lubricating oils .produced fromparaifin base.

crudes exhibits. high valuea 7 It is one of the characteristics, of thelubricating oil produced by our process that it posses,-

ses a low Conradson carbon value. In Table I Conradson carbon values areshown for a typical. parafiin base, lubricating oil, a. typicalasphaltic base lubricating oil by our process.

" "TABLEI" "Conradson carbon values Another desirable quality oflubricating oil is a high resistance towards oxidation. In general oilswhich oxidize less rapidly are to be preferred. Lubricating oilsproduced from paraffin base crudes have less tendency to oxidize thanlubricating oils produced by the distillation of asphalt base crudes. Itis one of the charand atypical oil produced acteristics of the oilproduced by our process from asphalt base crudes containing wax that itpossesses a low oxidation .value.

-One of the methods used to' determine the oxidation value of an oil isto be found in the v Proceedings of the American Society of TestingMaterials, Volume 24, Part II of l924, page 964, and is sometimes knownas the Slighmethod. In Table II'there is shown a comparison of theoxidation values of a lubricating oil produced from paraflin base crude,a lubricating oil produced by our process from asphalt base crudescontaining wax, and a lubricating oil produced by the d stillation ofasphaltbase crude:

TABLE'II Sligh ,oridation values 7 Sligh oxidation values Paraflin baselubricating: oil produced from Pennsylvania crude 5.0 Asphaltic baselubricating oil produced by our process from California crude 4.0Asphaltic base lubricating oil produced from California crud e 40.0

Generally stated. it is the object of our invention toisolate from crudeoil those oils having characteristics which impart to it the lowtemperature viscosity susceptibility typical of paraffin baseoil.

More particularly, it is an object of our invention to isolate fromasphalt containing oils those components which impart to the oil thereduced susceptibility to change in viscosity with temperature which ischaracteristic of oils obtained from non-asphalt containing oils; thatis, to separate the parafiinoid from the non-paraifinoid components ofthe'asphalt containing crude oils.

It is more particularly an object of our invention to isolate fromasphalt containing'oils'those lubricating oil components which we callparaffinoid and whichresemble the lubricating oils produced frompetroleum crudes substantially free of asphalt but to conserve thosepeculiar properties of asphalt crudes which impart to the lubricatingOilsobtained therefrom a relatively low Conradsoncarbon value ascompared with oils produced from paraflin base'crudes.

It is-a further object of our invention to precipitate asphalt from anoil containing asphalt with'liquid propane and thereafter to extract oilwith liquid sulphur dioxide with an end in view of obtaining anoil'relatively insoluble in liquid sulphur dioxide'and which is freefromasphalt and which has characteristics resemblingoils' producedfrom'c'rudes substantially free'ot asphalt.

-It i'sa' further object of our invention to isolate from'asphaltcontainingoil those lubricating oils which exhibit a relatively lowviscosity temperature susceptibility and which passes a' relatively lowConradson carbon value.

It is a further object'of our invention to separate oil and wax fromasphalt bearing crude by the use of liquid propane, to separate the waxfrom the oil, to resolve the oil into a portion having non-paraflinoidcharacteristics and a portion having parafiinoid characteristics and totreat the latter oil with sulphuric acid for the purpose of removingfurther impurities.

It is a further object of our invention to proby referring to thedrawings.

Fig. 1 is a set of curves representing viscosity temperaturerelationships of an oil produced by extraction from an asphaltcontaining oil.

Fig. 2 is a set of curves representing tempera ture viscosityrelationships of an oil produced by treatment of the oil shown in Fig. 1toremove fractions which increase its temperature viscositysusceptibility.

Fig. 3 is a schematic arrangement of one form of the apparatus in whichour process may be carried out.

Fig. 4 is a schematic arrangement of another form of the apparatus inwhich our process may be carried out.

Referring more particularly to Fig. 3, the crude oil from which all ofthe gasoline, kerosene and gas oil have been removed in tank 1 iswithdrawn through valve 2 and sent by means of pump 3 to line 4 where itmeets a stream of liquid propane coming from storage tank 11 throughvalve 12, pump 13 and line 14. The mixture of topped crude and liquidpropane passes into chiller 5 where the mass is'cooled by allowing aportion of the liquid propane to vaporize under reduced pressure throughvalve 6 into line '1. Thevaporized propane in line 1 is compressed bycompressor 8. and sent to condenser 9 where it is liquefied and passesby means of line 10 to propane storage tank 11.

The cooled mass of topped crude and liquid propane in chiller 5 passesby means of line to agitator 16 where it is thoroughly mixed, afterwhlch'it passes by means of line 17 to decanter 18 where the asphaltsettles out.

The asphalt in decanter 18 is removed through valve 19 and sent by pump20 through line 21 to heater 22 where the temperature of the mass israised sufficiently to vaporize all the propane and moisture present.passes by means oi line 23 into separator 24 where the asphalt separatesout and is removed through valve 25 and line 26 to storage tank 27. Themixture of water vapor and propane passes from separator 24 through line28 to condenser 29' -where the water vapor is condensed. The mixture ofwater and propane vapor passes from condenser 29 to separator 30 wherethe water is separated out and is removed through valve 31 and line 32.The propane vapor in separator 30 passes by means of line 33 tocompressor 34 where it is compressed and sent by means of line 33' tocondenser 9 where it is liquefied and. passes through line 10 to storagetank 11.

The propane solution or oil in decanter 18 is withdrawn through line 35and passes into chiller 36 where the temperature of the mass is loweredto a point suflicient to cause thorough wax precipitation by allowing aportion of the propane present in chiller 36 to vaporize and reducepressure through valve 37 into line 38. The propane vapor in line 38 iscompressed by compressor 39 and sent through line 38 to condenser 9where it is liquefied and passes by means of line 10 to storage tank 11.r

The cooled mass in chiller 36 is withdrawn through valve 40 and line 41whereafter it is sent by pump 42 to a dewaxing stage which may consistin centrifuging, filtering and cold settling the chilled mass to removethe wax. The de- -valve 53 and sent The heated mass then' waxed oildissolved in liquid propane emerges from the dewaxing stage into line 44where it is mixed with sulphuric acid coming from tank 45 through valve46, line 47, compressor 48 and line 47'. The mixture of oil and acidthen passes into agitator 49 where they are thoroughly mixed after whichthey pass into decanter 51'where the sludge is allowed to settle out.

The sludge in decanter 51 is removedthrough by means of pump 54 throughline 55 to heater 56 where the temperature of the mass is raisedsufliciently to vaporize the propane. The heated mass then passes bymeans of line 57 to separator 58 where the sludge separates out and iswithdrawn through valve 59 and line 60. The propane vapor passes fromseparator 58 through line 61 to scrubbing tower 62 where it is contactedwith liquid caustic soda to rem'ove any sulphur dioxide present. Thescrubbed propane passes from tower 62 through valve 66, line 6'1,compressor 68, line 6'1 to condenser 9 where it is liquefied and passesby means of line 10 to storage tank 11.

The acid treated oil dissolved'in propane in decanter 51 passes by meansof line 52 to clay tower 125 where any remaining sludge is removed. Thepropane solution of treated oil then passes from tower 104 by means ofline 69 to evaporator'lfl where the propane present is vaporized withthe aid of steam introduced through closed steam coil 74. The propanevaporpasses from evaporator '70 through valve 71 into line- '12 thenceto compressor 73.. where it is compressed and sent by means of line 72to condenser '9 where it is liquefied and passes by means of line 10 tostorage tank 11. The propane free oil in evaporator is withdrawn throughvalve '15 and passes through cooler 76 where the temperature is loweredsufliciently for extraction of the sulphur dioxide. The cooled oilpasses from cooler '16 to pump 7'7 which forces it through line 78 intothe lower zone of extraction column 104.' Liquid sulphur dioxide fromtank 79 is withdrawn through valve 80 into line 81 and is forced by pump82 through line 81' into the upper zone or extraction column 104. Due tothe difference in specific gravity of oil introduced into the lower zoneof extraction column 104 and the sulphur dioxide introduced into theupper zoneof extraction column, these two liquids tend to separate. Asthe heavy liquid sulphur dioxide passes down through the ascendingcolumn of oil it dissolves certain constituents present which areremoved in the form of a sulphur dioxide solution through valve 94 intoline 95 from which it passes into evaporator-96 wherethe sulphur dioxidepresent is removed with the aid of steam introduced in closed steam coil105 and passes through valve 9'? into line 90 and thence to compressor101 where it is compressed and passes by means of line 90' to condenser102 where it is liquefied and passes by means of line 103 to sulphurdioxide storage 79.

The ascending column of oil in column 104 from which there has beenremoved the sulphur dioxide soluble constituents passes through valve 83and line 84 into auxiliary settling chamber 85 where any remainingliquid sulphur dioxide settles out. The settled oil from chamber 85passes through line 8'7 into evaporator 88 wherethe sulphur dioxidepresent is vaporized by aid of steam introduced into closed steam coil106 and passes through valve 89 to line 90 and thence to compressor 101where it is compressed and sent through line 90 to condenser 102 whereit is liquefied and passes by means of line 103 to sulphur tank 11through valve 12, pump 13 and line 14.

The mixture of topped oil and propane passes into chiller where thetemperature of'the mass is lowered by allowing a portion of the propaneto vaporize at a. reduced pressure through ,valve 6 into line 7 fromwhence it passes to compressor 8 where it is compressedand passes tocondenser 9 where it is liquefied and passes by meansof line 10 topropane storage tank 11.

The cooled mixture of topped oil and liquid propane passes from chiller5 through line to agitator 16 where the mass is thoroughly agitatedafter which it passes by means of line 17 to decanter 18 where theasphalt is allowed to separate out.

The asphalt in decanter 18 is withdrawn through valve 19 and sent bymeans of pump 20 through line 21 to heater22 where the temperature ofthe mass is raised sufficiently to vaporize the propane and moisturepresent. The heated mass then passes by means of line 23 into separator24 where the asphalt separates out and is withdrawn through valve 25 andline 26 into storage tank 27. .The mixture of propane vapor and watervapor passes by means of line 28 through condenser 29 where any moisturepresent is condensed. The mixture of water and propane vapor passes intoseparator 30 where the water is removed through valve 31 and line 32.The propane vapor in separator 30 passes by means of line 33 tocompressor 34 where it is compressed and passes bymeans of line 33' tocondenser 9 where it is liquefied and passes by means of line 10 'tostorage tank 11. v

The propane solution of oil in decanter 18 passes through line 35tochiller 36 where the temperature, of the mass is lowered sufllcientlyto cause a thorough precipitation 01' the wax by allowing a portion of.the propane present to vaporize under reduced pressure through valve 37into line, 38 from whence it passes to compressor- 39 where it iscompressed and sent through line 38' to condenser 9 where it isliquefled and passes by means of line 10 into storage tank 11. Thecooled mass in chiller 36 is withdrawn through valve 40 and line 41 andsent by means of pump 42 through the dewaxing-stage 43 which may consistof centrifuging, filtering or cold settling to remove the wax present.The dewaxed oil emerges from the dewaxing stage 43 through line 44 andpasses into evaporator 70 where the propane present is vaporized bytheaid of heat introduced through closed steam coil 74. The vaporizedpropane passes from evaporator 70 through valve 71 and compressor 73where it is compressed and is sent by means of line 72 and line 38' tocondenser 9 where it'is liquefied and passes by means of line 10 tostorage tank 11. The propane free oil in evaporator '70 is withdrawnthrough valve 75 and line 75' and sent by means of pump 77 throughcooler '16 where the temperatureof theoil is lowered sufliciently beforeextraction with sulphur dioxide. The cooled oil in cooler 76 passes bymeansvof line 78 into the lower zone of extraction column 104. Liquidsulphur dioxide from storage tank '79 is withdrawn through valve 80 andline 81 to pump 82 which sends it through line 81' -,to the upper zoneof extraction column 104. Due to the difference in specific gravity ofthe sulphur dioxide introduced into the upper zone of the extractioncol-" umn and the oil introduced into the lower zone of the extractioncolumn, these two liquids tend to separate. The heavy liquid sulphurdioxide passing down through extraction column 104 removes certaincomponents from the oil present in the column in the form of a-sulphurdioxide] solution. This solution is withdrawn through valve 94 intoline- 95 and passes into evaporator 96 where the sulphur dioxide presentis vaporized with the aid of steam introduced through closed coil 105.The vaporized sulphur dioxide passes from evaporator 96 through valve 97into line 90 and thence to compressor 101 where it. is compressed andsent by means of line 90 to condenser 102 where it is liquefied and.passes by means of line 103 to sulphur dioxide storage tank 79. Thesulphur dioxide tree oil in evaporator 96 is withdrawn through valve 98and passes by means of line 99 to storage tank 100.

The ascending column or oil in extraction col-. umn 104 from which thesulphur dioxide soluble components have been removed is withdrawnthrough valve 83 into line 84 from whence it passes into auxiliarysettling chamber where any remaining liquid sulphur dioxide is settledout. The settled oil in chamber 85 passes through line 87 intoevaporator 88 where the sulphur dioxide present is vaporized with theaid of steam introduced through closed coil 106. The sulphur dioxidevapor in vaporizer 88 passes by means of valve'89 into line and thenceto compressor 101 where it is compresed and passes by means of line 90'to condenser 102 where it is liquefied and passes by means of line 103to liquid sulphur dioxide storage 79. The sulphur dioxide free oil invaporizer 88 is withdrawn through valve 91, and sent by means of line 92to pump 114 which forces it into line 115 where it is re-dissolved byliquid propane coming from storage tank 11 through valve 117, pump 118,line 120. The propane solution or oil is then mixed with sulphur dioxidecoming from tank 45 through valve 46, line 47. pump 48 and line 4'7. Themixture. of asphalt and oil, in line 115 passes into agitator 49 whereit is thoroughly mixed, after which it passes into separator 51 wherethe sludge is allowed to separate out.

The sludge in separator 51 is withdrawn through valve 53 and sent bymeans of pump 54 through line 55 to heater 56 where the tem perature ofthe mass is raised sufficiently to vaporize the propane present. Theheated mass passes from heater 56 through line 5'? to separator 58 wherethe sludge separates out and is withdrawn through valve 59 and line 60and sent to s ludgetank 113. The propane vapor in separator 58 passes bymeansof line 61 through scrubbing tower 62 "where it is contacted withliquid caustic soda to remove any sulphur dioxide present. The scrubbedpropane passes from tower 62 through line 67 to compressor 68 where itis compressed and sent by means of line 67" and line 33'- to condenser 9where it is liquefied and passes'by means of line 10 to storage tank 11.

The acid treated oil dissolved in the propane is withdrawn from settlingchamber 51 through line 52 and sent through clay" tower which removesany remaining sludge present, after which it passes by means of line 69to evaporator 119 where the propane present .is vaporized with Thetopped oil in tank 1 of Fig. 3'at a 'temperature approximating 200 F. ismixed with liquid propane and cooled by allowing a portion of thepropane present to vaporize until a temperature of about 120 F. isattained, after which the'mixture of residual oil and propane is mixedin agitator 17. The thoroughly agitated mass passes into decanter 18where the propane solution of oil and wax is separated from theundissolved asphalt. This oil dissolved in liquid propane which is amixture of paraffinoid and non-paraffinoid oils possessing about 54%,parafiin base characteristics is chilled sufficiently to cause the waxpresent to precipitate out by allowing a further portion of the propanepresent to vaporize under reduced pressure. The precipitated wax isremoved from the solvent solution of oil by such means as cold settling,centrifuging, or filter pressing. The oil, substantially free of wax andasphalt dissolved in solvent, is next treated with sulphuric acidintroduced from tank 45. The result of this treatment is to removefurther quantities of undesirable bodies present in the oil which tendto give the finished product an increased viscosity temperaturesusceptibility. After treatment with sulphuric acid the oil is separatedfrom the solvent and then extracted.

with liquid sulphur dioxide for the purpose of separating theparafilnoid from the non-parafilnoid constituents. Curve C of Fig. 2 isrepresentative of an oil obtained by our process and. exhibits 62%paraflin base characteristics. Ashas been explained in the foregoingdescription, it has been found advisable in some cases-to perform theacid treatment subsequent to treatment with liquid sulphur dioxide. Theprocess as set forth in Fig. 4 is illustrative of this mode ofoperation.

The foregoing exemplary description is merely illustrative of apreferred mode of carrying out our invention and is not to be taken aslimiting, as many variations may be made within the scope of thefollowing claims by a person skilled in the art without departing fromthe spirit thereof.

We claim:

1. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent, to separate asphalt, removing the asphalt from theoil and wax dissolved in said solvent, chilling the solvent solution ofoil and wax to precipitate wax, separating the wax from the oil andsolvent, separating the solvent from the oil, extracting saidsubstantially asphalt and wax free oil with a selective solvent to forma parafiinoid fraction and a non-paraifinoid fraction and separatingsaid fractions.

2. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent under superatmospheric pressure to separate asphalt,removing the asphalt from the oil and wax dissolved in said solvent,releasing the pressure on said oil and.

wax dissolved in said solvent and vaporizing a portion of said solventto chill'the'oil and precipitate wax, separating the precipitated waxfrom the oil and remaining solvent, removing the remaining solvent fromthe oil, extracting the substantially asphalt and wax free oil with aselective solvent to form a paraflinoid fraction and a non-parafiinoidfraction and separating said fractions.

3. A process as in claim 1 in which the'selective solvent is sulphurdioxide. Y

4. A method for the treatment of oil containing asphalt and wax whichcomprises commin-' gling said 011 with a liquefied normally gaseoushydrocarbon solvent containing a major portion of propane to separateasphalt. removing the asphalt'from the oil and wax dissolved in saidsolvent, cooling the solvent solution of, oil and wax to precipitatewax, separating the precipitated wax from the oil and solvent, removingthe solvent from the substantially asphalt and wax free oil, extractingthe substantially asphalt and wax free oilwith a selective solvent toform a parafiinoid fraction and a non-parafiinoid fraction andseparating said fractions.

5. A process as in claim 4 in which the selective solvent is sulphurdioxide.

- 6. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent to separate asphalt, separating the asphalt from theoil and wax dissolved in said solvent, chemically treating the oil andwax dissolved in said solvent, chilling the treated solution of asphaltand wax to precipitate wax, separating the solvent from thesubstantially asphalt and wax free oil, extracting the substantiallyasphalt and wax freev oil with a selective solvent to form a parafflnoidfraction and a nonparafiin'oid fraction and separating said fractions.

'1. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent containing a major portion of propane to separateasphalt, separating the asphalt from the oil and wax dissolved in saidsolvent, chilling the solvent solution of oil and wax to precipitate.wax, separating the precipitated wax from the oil and solvent,chemically treating the substantially asphalt and wax free 011 dissolvedin said solvent, separating the solvent from the'substantially asphaltand wax free oil, extracting the substantially asphalt and wax free 011with a selective solvent to form a parafllnoid fraction and anon-parafiinoid fraction and separating said fractions.

8. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil under superatmospheric pressure with aliquefied normally gaseous hydrocarbon solvent, containing a majorportion of; propane. to separate asphalt, separating the asphalt fromthe oil and wax dissolved in said solvent releasing the pressure on thesolvent solution, of oil and vaporizing a portion of the solvent tochill the 'oil and precipitate wax,- separating the precipitated waxfrom the oil and remaining solvent, chemically treating thesubstantially asphalt and wax free oil dissolved in the remainingsolvent, removing the remaining solvent from the oil, extracting thesubstantially asphalt and wax free oil with a selective solvent to forma parafiinoid and a non-paraflinoid fraction and separating saidfractions.

9. A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent to precipitate asphalt, separating the precipitatedasphalt from the oil and wax dissolved in said solvent, chilling thesolvent solution of oil and wax to precipitate wax, separating the waxfrom the oil and solvent, removing the solvent from the substantiallyasphalt and wax free oil, extracting said substantially asphalt and waxtree oil with a selective solvent to form a parafllnoid fraction and anonparafiinoid fraction, separating said fractions and chemicallytreating the paraflinoid fraction.

10 A process as in claim 9 in which the chemical treatment is carriedout in the presence of a liquefied normally gaseous hydrocarbon solvent.

11. A method for the treatment of oil contain- Patent No. 1,988, 712

ing asphalt and wax which comprises commingling said oil undersuperatmospheric pressure with a liquefied normally gaseous hydrocarbonsolvent containing a major portion of hydrocarbons of less than fourcarbon atoms to separate asphalt, separating the asphalt from the oiland wax dissolved in said solvent, releasing the pressure on saidsolvent solution of oil and wax and vaporizing a portion of the solventto chill the oil and precipitate wax, separating the precipitated waxfrom the oil dissolved in the remaining solvent, removing the remainingsolvent from the oil, extracting the substantially asphalt and wax freeoil with a selective solvent to form a parafilnoid fracton and anon-parafllnoid frac- January 22, 1935.

- ULRIC B. BRAY, ET AL.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correct after "the" in the PatentOffice.

insert the word same; page 6, reference claim number "1" read 2; andthat the said Letters with these corrections therein that the same maycon line 11,

d olumn, sewn 6 Patent should be read Signed and sealed this 9th day ofApril, A. D. 1935.

Leslie Frazer.

Acting Commissioner of Patents.

form to the record of the case on" lncnlnfiwn ,Monsanto. .l c t g n w, n3/ 3 7 CERTIFICATE or CRRECTION.

' .Pa e 1, second column, line 1. [011 as follows g claim 3 for the I 9.A method for the treatment of oil containing asphalt and wax whichcomprises commingling said oil with a liquefied normally gaseoushydrocarbon solvent to precipitate asphalt, separating the precipitatedasphalt from the oil and wax dissolved in said solvent, chilling thesolvent solution of oil and wax to precipitate wax, separating the waxfrom the oil and solvent, removing the solvent from the substantiallyasphalt and wax free oil, extracting said substantially asphalt and waxtree oil with a selective solvent to form a parafllnoid fraction and anonparafiinoid fraction, separating said fractions and chemicallytreating the paraflinoid fraction.

10 A process as in claim 9 in which the chemical treatment is carriedout in the presence of a liquefied normally gaseous hydrocarbon solvent.

11. A method for the treatment of oil contain- Patent No. 1,988, 712

ing asphalt and wax which comprises commingling said oil undersuperatmospheric pressure with a liquefied normally gaseous hydrocarbonsolvent containing a major portion of hydrocarbons of less than fourcarbon atoms to separate asphalt, separating the asphalt from the oiland wax dissolved in said solvent, releasing the pressure on saidsolvent solution of oil and wax and vaporizing a portion of the solventto chill the oil and precipitate wax, separating the precipitated waxfrom the oil dissolved in the remaining solvent, removing the remainingsolvent from the oil, extracting the substantially asphalt and wax freeoil with a selective solvent to form a parafilnoid fracton and anon-parafllnoid frac- January 22, 1935.

- ULRIC B. BRAY, ET AL.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correct after "the" in the PatentOffice.

insert the word same; page 6, reference claim number "1" read 2; andthat the said Letters with these corrections therein that the same maycon line 11,

d olumn, sewn 6 Patent should be read Signed and sealed this 9th day ofApril, A. D. 1935.

Leslie Frazer.

Acting Commissioner of Patents.

form to the record of the case on" lncnlnfiwn ,Monsanto. .l c t g n w, n3/ 3 7 CERTIFICATE or CRRECTION.

' .Pa e 1, second column, line 1. [011 as follows g claim 3 for the I

